The present invention relates to a molding die of a laminated molding. More specifically, the present invention relates to a molding die of laminated molding having a molding body made of synthetic resin and a compressible surface member laminated thereto, and a producing method for the laminated molding.
Conventionally, products made of synthetic resin are used for interior goods of an automobile, parts of an electric appliance, household commodities etc.
Among the synthetic-resin-made products, an air-current control valve of an air conditioner for an automobile has flexible-and compressible surface members for securing sealability thereof. Further, a frame-shaped surface member as a sealing member is provided around an opening of an air-cleaner case for an automobile and a peripheral portion of an inner side of a refrigerator door in order to enhance air-tightness thereof.
Such moldings having a synthetic-resin-made molding body as a base and a surface member integrated thereto can be manufactured by the following method:
(1) Attaching the surface member by adhesive or the like onto a surface of a molding body manufactured in advance according to injection molding method or the like;
(2) Utilizing an injection molding method, where molten resin is injected into a die for integrally molding the molding body with the surface member after closing the die with the surface member being disposed therein (Japanese Patent Application Laid-open No. Hei 3-60297); and
(3) Utilizing an injection press molding method, where the surface member is disposed inside the die, and the molten resin is filled inside the die and is compressed by closing and clamping the die (Japanese Patent Application Laid-open No. Hei 5-83056).
However, following disadvantages could occur according to the above methods.
Since the surface member has to be attached onto the molding after shaping the moldings according to the above (1) method, lot of work is required and the productivity can be lowered.
According to method (2) and (3), since the surface member can be integrated simultaneously with the shaping step, the productivity can be enhanced. However, a compressible surface member such as polyurethane foamed sheet is difficult to be accurately disposed to a predetermined position inside the molding die, the position of the surface member is likely to be shifted relative to the molding body from the predetermined position.
Especially, when the surface member is partially laminated to the molding body, since the surface member is required to be partially disposed to the inner surface (molding surface) of the molding die body, accurate positioning gets more difficult and the surface member is likely to be shifted.
Further, when the molten resin is injected into the inside of the molding die having the surface member disposed therein, the surface member can be pushed away by the resin pressure to cause position shift.
An object of the present invention is to provide a molding die of laminated molding and a producing method of the laminated molding, where the surface member can be accurately and easily disposed at a predetermined position inside the molding die.
Another object of the present invention is to provide a molding die of laminated molding and a producing method of the laminated molding, where the surface member can be accurately and easily disposed at a predetermined position inside the molding die and, further, a position shift of a surface member by a resin pressure during molding process can be prevented.
The present invention is a molding die of laminated molding for shaping the laminated molding having a molding body made of synthetic resin and a compressible surface member laminated thereonto, the molding die having a die body containing a cavity for shaping the laminated molding thereinside and a centering pin provided protrudably and retractably into the cavity for determining a position of the surface member.
In the above, the surface member includes any member that is laminated on a surface of the molding body, which may be, for instance, sheet-shaped member and belt-shaped member and the like.
Since the centering pin for determining the position of the surface member is provided in the present invention, the surface member can be accurately and easily positioned and can be kept in the condition at the predetermined position in the cavity by only engaging a predetermined portion of the surface member to the centering pin, thereby securely preventing position shift of the surface member.
Further, since the centering pin is disposed protrudably and retractably into the cavity, the molten resin can be flown into a projecting portion of the centering pin in the cavity by retracting the centering pin before the molten resin is solidified, thereby obtaining laminated moldings having good quality and appearance.
Formed sheet made of resin such as, for instance, polyurethane, polystyrene and polyethylene, and a laminated sheet integrated with other facing member such as film at least on one side of the formed sheet can be used as the surface member.
The facing member may preferably be a general film and sheet, a resin-made sheet and film having decorative patterns printed thereon, woven fabric and non-woven fabric or the like.
The synthetic resin constituting the molding body as a base may preferably be a thermoplastic resin such as polypropylene, polystyrene, polyethylene, ABS, polycarbonate, and composition of various additives to the thermoplastic resin.
The additives may be filler such as talc, mica and glass fiber, stabilizing agent for preventing deterioration by heat, light etc., and coloring agent.
The die body may preferably include a stationary die and a movable die advanceable and retractable relative to the stationary die, and the centering pin may protrude into and retract from the cavity in synchronization with advancement and retraction of the movable die.
In other words, when the centering pin protrudes synchronizing with the retraction of the movable die (opening the mold) and the centering pin retracts synchronizing with the advancement of the movable die (clamping the mold), the surface member can be easily and securely positioned by the centering pin since the centering pin can be protruded by only opening the die body.
Further, since the centering pin can be retracted when the die body is closed, the portion where the centering pin protrudes in the cavity can be securely filled by the resin, thereby obtaining good appearance.
In the above, the centering pin is preferably provided respectively to the stationary die and the movable die.
By providing the centering pins on both of the stationary die and the movable die, the surface members can be laminated on both sides of the molding body without causing position shift.
The die body may further include a slide die advanceable and retractable relative to the cavity, and the centering pin may retract from the cavity in accordance with the advancement of the slide die.
By retracing the centering pin in accordance with the advancement of the slide die, the position-determined surface member can be retained to the protruding centering pin until the completion of the advancement of the slide die, i.e., until the completion of compression of the molten resin, when the slide die is advanced to compress the molten resin, thereby conducting injection compression molding. Accordingly, since the surface member can be retained on the centering pin until the compression is completed and the molten resin substantially stops flowing, the surface member can not easily be pushed away by the resin flow, so that the position shift of the surface member by the resin pressure can be avoided.
Further, by advancing the slide die to compress the molten resin, the molten resin can be securely spread (filled) into the entirety of the cavity. Therefore, the molding body corresponding to the cavity configuration can be obtained and the molten resin can be securely flown into the portion where the centering pin is protruded in the cavity, the portion where the centering pin protruded in the cavity can be securely filled up.
The centering pin may be provided respectively to the slide die and a portion of the die body opposite to the slide die.
By opposingly providing the centering pins to the cavity, the surface member can be securely laminated on both sides of the molding body without causing position shift.
Another aspect of the present invention is a producing method of laminated molding for integrally shaping the laminated molding, the laminated molding having a molding body made of synthetic resin and a compressible surface member laminated thereonto. The producing method includes the steps of; providing a molding die having a molding body including a cavity for shaping the laminated molding and a centering pin protrudable and retractable relative to the cavity; protruding the centering pin relative to the cavity to determine a position of the surface member by piercing a predetermined portion of the surface member with the centering pin; and injecting a molten resin into the cavity to perform injection molding or injection compression molding.
In the present invention, since the surface member is positioned by piercing the surface member to the centering pin of the molding die, the surface member can be positioned accurately and easily to a predetermined position in the cavity and can be retained in the condition, so that the position shift of the surface member can be securely prevented.
In the above, after determining the position of the surface member, the molding body is preferably closed simultaneously with compression of the surface member and the molten resin is preferably injected into the cavity while the molding die is closed and the surface member is compressed.
By compressing the surface member of which position is determined, the surface member can be retained while the position of the surface member is determined. Therefore, the surface member can be prevented from being pushed away by the flow of the molten resin, thereby preventing position shift of the surface material by the resin pressure.
Further, the die body preferably includes a slide die advanceable and retractable relative to the cavity, the surface member is preferably compressed by advancing the slide die relative to the cavity, the slide die is preferably temporarily retracted relative to the cavity after initiation of the injection of the molten resin, and the slide die is preferably advanced toward the cavity to compress the molten resin.
By compressing the surface member by the advancement of the slide die, the surface member can be sandwiched between the slide die and a portion of the slide die opposing the die body, thereby fixing the surface member in a condition where the position of the surface member is determined.
Further, since the slide die is once retracted after the completion of the injection, the injection pressure can be set low, thereby largely decreasing damage applied on the surface member.
Since the retracted slide die is re-advanced, the molten resin can be spread to the entirety of the cavity, thereby obtaining superior moldability.